GB1574474A - Pendant switch device - Google Patents

Description

(54) PENDANT SWITCH DEVICE (71) We, LA TELEMECANIQUE ELEC TRIQUE, a French Body Corporate, of 33 bis and 33 ter Avenue du Marechal Joffre, F 92000 Nanterre, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention concerns a pendant switch device.

Such switch devices are, in particular, used to control the movements of travelling gantries where the operator remains on the ground.

In pendant switch devices designed for this type of application an attempt is usualy made to make the movements of the operator's hand instinctive, e.g. by providing the switch device with one or several operating components whose movements are parallel to the movements to be carried out.

Thus, a vertically moving component will be associated with the "lifting" and "lowering" movements of a crane or gantry hook and a sideways-moving component will be associated with its "righthand" and "left-hand" movements.

These arrangements do, however, lead to difficulties, since the range of the possible movements of the fingers, especially the range of movement of the tumb, is relatively limited, especially when the other fingers of the hand have to be used to hold a casing of the switch device.

It is the object of the invention to provide a pendant switch device wherein the numbers of components to be operated with the fingers is reduced to a minimum and wherein the actuating components are protected as far as possible from the effect of the disturbing factors present in industrial environment, such as those caused by dust, damp and knocks.

According to the present invention, a pendant switch device comprises: (i) an assembly of a first members and a second member coupled together such that when one is moved from a rest position the other performs a relative movement under the action of gravity, the first member being a housing and the second member being disposed within the housing, (ii) a plurality of switch or valve means disposed within said housing and operable as a result of said relative movement of the other member, when said members are moved from a first relative position to a second relative position, (iii) a cable secured to one of the mem bers to carry the assembly and in cluding electrical conductors con nected to or for connection to the switch means, or fluid flow conduits connected to or for connection to the valve means, (iv) a safety device carried by the hous ing and accessible from the exterior for manual operation, the safety device having a rest condition in which (a) it prevents such operation of the switch means or valve means, or (b) breaks continuity between the conductors and the switch means, or between the conduits and the valve means, said safety device having a manually-actuated condition in which (a) it permits such operation or (b) provides such continuity.

It will be observed that electric switches which react to a change in their position are known per se; however, these devices, which are generally intended for detecting faults or breakdowns, are not designed to carry out frequent operating cycles and are not combined with safety means.

Other features of the invention, aimed at increasing safety and improving switching performance will be better understood from a reading of the ensuing description with reference to the accompanying drawings, wherein: Fig. 1 shows, in section, a pendant switch device in which a heavy body is a pendulum within a box; Fig. 2 shows, in section, another embodiment wherein a box is tiltable relative to a cable; Figure 3 shows, also in section, yet another embodiment in which a heavy body is a column of mercury; Figures 4, 5 and 6 show mechanical safety devices applicable to the pendant switch devices according to the invention; and Figures 7, 8 and 9 show modified embodiments suitable for use in conditions where switching must be carried out without operating electric contacts, e.g. for applications in an explosive atmosphere.

The pendant switch device shown in Figure 1 comprises a box 2 hung from a hanging cable 1 by means of a nut 11 and stuffing 30. It is assumed that the cable not only contains the electric conductors but also a support member such as a cord which prevents longitudinal mechanical stress on the conductors, and also that the cable is sufficiently flexible to allow it to be bent, at least in the area of a hollow in the nut, formed in the vicinity of the end 12 of said cable.

The box contains an actuating component consisting of a heavy pendulum 3 which is movable in relation to the box, by means of a pivot 4 from which the pendulum hangs. This pendulum tends to remain parallel to the vertical direction (VV'). In the vicinity of the end of the pendulum there are, on each side of it, two switches 5 and 6, while the pressbutton 7 of a third switch 8 protrudes outside the box, opposite a protective handle 9.

A press-button 10 on the front of the box, opposite push-button 7, is designed to operate one or several switches, not shown in fig. 1 but which can be seen at 13-14 in Figure 2, whose function is to start or stop the " lifting " and " lowering " movements of the hook of a lifting gear.

The output terminals of switches 5 and 6 are respectively associated with electrical devices controlling the "backward" and "forward" movements and are supplied by a current source which is cut off by switch 8 when the latter's push-button 7 is not operated, consequently acting as a safety switch sometimes called a "dead man ".

When the operator picks up the box, he can slant it in such a way that the relative movement between the box and the pendulum causes the latter to operate one of switches 5, 6 but the order will only be transmitted if push-button 7 is simultaneously operated, e.g. with the index finger; in these circumstances, operating pushbutton 10 wtih the thumb is still possible.

Though they have not been illustrated in the drawings, further switches relating to the "right" and "left" controls, are positioned on each side of the pendulum, at right angles to the plane of the figure, provided that the pivot 4 be replaced by a universal ball-and-socket joint.

The operation of such further switches would be caused by a sideways slant, which could be combined with a "backward" or "forward" slant to obtain composite movements.

Due to the presence of switch 8 in the supply circuit to switches 5 and 6, no knock or movement of the box, caused in the absence of the operator, can be followed by the issuance of an order.

In the example in Figure 3, the components which have the same functions as those defined above bear the same reference numbers, but the actuating component consists of a certain quantity of conductive liquid 33, e.g. mercury, contained in a Ushaped container 37. The switches consist of this conductive liquid associated with two electrodes 36, 35 which are present within the container, and a supply electrode 34 is present within the bottom thereof.

The position of equilibrium of the actuating component is here a position where the levels in the two limbs of the U-shaped container lie along the same horizontal line HH'.

It is not always desirable or possible to ensure that cable 1 is flexible; in some devices, this cable is even a flat cable, which has relatively high rigidity, at least in one direction. Moreover, it may be desired not to cause fatigue in the conductors and the supporting cord by repeated folding.

In this case, the modified embodiment illustrated in Fig. 2 make it possible to take advantage of the usefulness and simplicity of the device just described without bending the cable.

The actuating component tending to remain in a fixed position in space is here a support 23 integral with a stuffing box holding the cable. The stuffing box can even be fitted with a skirt 21 which ensures that the support 23 remains in the direction determined by the cable, hanging by its own weight.

In an area close to the stuffing-box, support 23 has a pivot or ball-and-socket joint 17 cooperating with a guide 24 positioned at the top of the box 2 so that the end 29 of support 23 undergoes a movement relative to the inside walls of the box when the latter is slanted. Although an arrangement of the "backward" and "forward" switches similar to the one described in Figure 1 has been adopted, it has been decided to arrange these (25, 26) on the end 29 of the support to reduce the number of electric conductors subjected to bending when the box is moved, and to make them cooperate with stops 27 and 28, possibly adjustable, placed in the box. An opening 15 in the support makes it possible to connect switches 25 and 26 to safety switch 8.

As in the previous case, "left" and "right" switches can be associated with the device.

It will be observed that the torque exerted on box 2 by the operator must be counterbalanced by a controlling torque supplied by slight bending of the cable beyond skirt 21.

Figures 4 and 5 show mechanical safety means each operated by a trigger 18 to prevent the issuance of an order by the switches (not shown) when this trigger means is not pressed by the operator.

In Figure 4, pendulum 3 is extended by an arm 20 the end of which is positioned opposite a centring surface 31 in the end of a lever pivoted at 32 and controlled by trigger means 18.

The centring surface 31, which can advantageously consist of a frusto-conical surface the top of which faces upwards, is subjected to the resilient effect of a spring 39 which causes it to move towards end 20 so that pendulum 3 is held in a central position where it cannot, in the absence of pressure on trigger means 18, exert any effect on the switches.

In Figure 6, movement of the pendulum is prevented by lowering a jacket 56, guided in a guide 58 in the box, by spring 54.

The walls of this jacket come down between the active end of pendulum 3 and the switches, so long as trigger means 18 has not caused said jacket to move by acting on an extension 57 with which it is integral.

When one of the devices described above is put into a slanted position to cause a movement, safety push-button 7, or trigger means 18 or 118 respectively must be operated to allow said movement; when it is wished to stop the latter, the box or operating component must be brought back to a vertical position and the safety push-button or trigger means must simultaneously be released, otherwise oscillations of these components in the opposite direction would be liable to cause brief excitation of the switch opposite the one which has just been operated.

A damper such as the one shown at 38 in Figure 4, and positioned between the pendulum and the box, can then be used to reduce the amplitude of the unwanted oscillation.

Alternatively, Figure 5 shows a device which enables pendulum 3 to assume the selected position by bending (as shown in dotted lines) of one of two resilient blades 53 or 52 which are integral with a movable support 54 and are positioned on each side of pendulum end 20; the support 54 has a portion 154 to restricted cross section located between the blades which limits the deformation of the blade which has just been cleared and prevents the pendulum from going beyond the neutral position when the box is brought back to the vertical. Trigger means 118 associated with support 54 can then be operated to make it possible, against spring 39, to replace pendulum end 20 between the blades.

When the pendant is to be used in an explosive atmosphere, it becomes necessary either to use sealed switches or to have recourse to electronic switches, or even pneumatic switches.

Examples of application to these environments are provided in Figures 7 and 8; in Figure 7, two photosensitive components 75, 76 are placed at the bottom of box 2 and can be illuminated through openings 81 and 80 respectively. A pendulum 74 consists of a tube pivoted by ball-and-socket joint 4. The bottom end 73 of said tube, when at rest, is between the two openings. The tube has its top end 71 close to the ball-and-socket joint in the area illuminated by a slight source 70.

Safety push-button 77 biassed by spring 78 carries a screen 72 which, in its "at rest " position, masks the light rays emitted by the source and may possibly operate an electronic switch 79.

In Figure 8, the end of pendulum 94 carries a metal or magnetic or magnetisable component 93 which takes up a position in the vicinity of proximity detectors, e.g. inductive, such as 95 and 96.

The device illustrated in Figure 9 comprises a pendulum 103 the free end of which can operate each of two pneumatic valves 105, 106 the fluid supply to which can be cut off by the safety component 108.

The box comprises an opening 109 in communication with atmosphere.

WHAT WE CLAIM IS: - 1. A pendant switch device comprising: (i) an assembly of a first member and a second member coupled together such that when one is moved from a rest position the other performs a relative movement under the action of gravity, the first member being a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. at the top of the box 2 so that the end 29 of support 23 undergoes a movement relative to the inside walls of the box when the latter is slanted. Although an arrangement of the "backward" and "forward" switches similar to the one described in Figure 1 has been adopted, it has been decided to arrange these (25, 26) on the end 29 of the support to reduce the number of electric conductors subjected to bending when the box is moved, and to make them cooperate with stops 27 and 28, possibly adjustable, placed in the box. An opening 15 in the support makes it possible to connect switches 25 and 26 to safety switch 8. As in the previous case, "left" and "right" switches can be associated with the device. It will be observed that the torque exerted on box 2 by the operator must be counterbalanced by a controlling torque supplied by slight bending of the cable beyond skirt 21. Figures 4 and 5 show mechanical safety means each operated by a trigger 18 to prevent the issuance of an order by the switches (not shown) when this trigger means is not pressed by the operator. In Figure 4, pendulum 3 is extended by an arm 20 the end of which is positioned opposite a centring surface 31 in the end of a lever pivoted at 32 and controlled by trigger means 18. The centring surface 31, which can advantageously consist of a frusto-conical surface the top of which faces upwards, is subjected to the resilient effect of a spring 39 which causes it to move towards end 20 so that pendulum 3 is held in a central position where it cannot, in the absence of pressure on trigger means 18, exert any effect on the switches. In Figure 6, movement of the pendulum is prevented by lowering a jacket 56, guided in a guide 58 in the box, by spring 54. The walls of this jacket come down between the active end of pendulum 3 and the switches, so long as trigger means 18 has not caused said jacket to move by acting on an extension 57 with which it is integral. When one of the devices described above is put into a slanted position to cause a movement, safety push-button 7, or trigger means 18 or 118 respectively must be operated to allow said movement; when it is wished to stop the latter, the box or operating component must be brought back to a vertical position and the safety push-button or trigger means must simultaneously be released, otherwise oscillations of these components in the opposite direction would be liable to cause brief excitation of the switch opposite the one which has just been operated. A damper such as the one shown at 38 in Figure 4, and positioned between the pendulum and the box, can then be used to reduce the amplitude of the unwanted oscillation. Alternatively, Figure 5 shows a device which enables pendulum 3 to assume the selected position by bending (as shown in dotted lines) of one of two resilient blades 53 or 52 which are integral with a movable support 54 and are positioned on each side of pendulum end 20; the support 54 has a portion 154 to restricted cross section located between the blades which limits the deformation of the blade which has just been cleared and prevents the pendulum from going beyond the neutral position when the box is brought back to the vertical. Trigger means 118 associated with support 54 can then be operated to make it possible, against spring 39, to replace pendulum end 20 between the blades. When the pendant is to be used in an explosive atmosphere, it becomes necessary either to use sealed switches or to have recourse to electronic switches, or even pneumatic switches. Examples of application to these environments are provided in Figures 7 and 8; in Figure 7, two photosensitive components 75, 76 are placed at the bottom of box 2 and can be illuminated through openings 81 and 80 respectively. A pendulum 74 consists of a tube pivoted by ball-and-socket joint 4. The bottom end 73 of said tube, when at rest, is between the two openings. The tube has its top end 71 close to the ball-and-socket joint in the area illuminated by a slight source 70. Safety push-button 77 biassed by spring 78 carries a screen 72 which, in its "at rest " position, masks the light rays emitted by the source and may possibly operate an electronic switch 79. In Figure 8, the end of pendulum 94 carries a metal or magnetic or magnetisable component 93 which takes up a position in the vicinity of proximity detectors, e.g. inductive, such as 95 and 96. The device illustrated in Figure 9 comprises a pendulum 103 the free end of which can operate each of two pneumatic valves 105, 106 the fluid supply to which can be cut off by the safety component 108. The box comprises an opening 109 in communication with atmosphere. WHAT WE CLAIM IS: -

1. A pendant switch device comprising: (i) an assembly of a first member and a second member coupled together such that when one is moved from a rest position the other performs a relative movement under the action of gravity, the first member being a

housing and the second member being disposed within the housing, (ii) a plurality of switch or valve means disposed within said housing and operable as a result of said relative movement of the other member, when said members are moved from a first relative position to a second relative position, (iii) a cable secured to one of the mem bers to carry the assembly and in cluding electrical conductors con nected to or for connection to the switch means, or fluid flow conduits connected to or for connection to the valve means, (iv) a safety device carried by the hous ing and accessible from the exterior for manual operation, the safety device having a rest condition in which (a) it prevents such operation of the switch means or valve means, or (b) breaks continuity between the conductors and the switch means, or between the conduits and the valve means, said safety device having a manually-actuated condi tion in which (a) it permits such operation or (b) provides such con tinuity.

2. A pendant switch device, as claimed in claim 1 wherein the second member is a pendulum and wherein the cable is flexible at least in the vicinity of the housing, said housing including a handle to facilitate moving of the housing with respect to the pendulum.

3. A pendant switch device, as claimed in claim 1, wherein the cable is rigid and the second member is rigidly connected to and extends the cable vertically, the housing and the second member being connected by a ball-and-socket joint, and the housing including a handle to facilitate moving of the housing with respect to the second member.

4. A pendant switch device, as claimed in any one of claims 1 to 3, wherein the switch means are mechanically-actuatable electrical switches mounted on the housing or on the second member.

5. A pendant switch device, as claimed in any one of claims 1 to 3, wherein the switch means are mounted on an inner surface of the housing.

6. A pendant switch device, as claimed in any one of claims 1 to 3, wherein the safety device is an electrical switch.

7. A pendant switch device, as claimed in claim 1, wherein the safety device is adapted, on its non-manually-operated condition, to prevent relative movement of the first and second members to their second position.

8. A pendant switch device, as claimed in claim 1 wherein the second member is a body of electrically conductive liquid contained in a U-shaped container, three conductors entering said container, and two of said conductors being in contact with the body of liquid in said second relative position of the first and second members.

9. A pendant switch device, as claimed in any one of claims 1 to 7, wherein the switch means are proximity switches respon sive to movement of the first and second members.

10. A pendant switch device, as claimed in any one of claims 1 to 5 and 7, wherein the valve means are pneumatic valves.

11. A pendant switch devices, as claimed in any one of claims 1 to 7, wherein the switch means include a photo-sensitive component responsive to variations in the intensity of light received from a light source consequent upon relative movement of the first and second members.

12. A pendant switch device, as claimed in any one of the preceding claims, comprising damping means connected between the first and second members.

13. A pendant switch device substantially as described herein with reference to any one of the figures of the accompanying drawings.